The present proposal mainly consists of four projects which include latency of EBV genomes, infection and superinfection with EBV, comparison of DNA of different virus strains and of EBV-like primate virus, and detection of EBV genome in tumors. The possibility of covalent integration of a few EBV DNA into cellular DNA will be examined by Southern blotting hybridization with each individual virus DNA fragment isolated. As the HR1 cell line was established by transforming virus but is shedding non-transforming virus, it will be studied whether or not HR1 cells still contain transforming virus DNA as well as nontransforming virus DNA within the multiple copies of latent EBV DNA. Attempts to isolate virus specific chromatin will be made to study the control mechanism of non-integrated plasmid virus DNA in Raji cells. Superinfection of Raji cells and infection of BJA-B cells with superinfecting HR1 virus or transforming B95 virus will be studied to examine to what extent the virus replication proceeds in these systems. None of these infection or superinfection result in complete replication of virus to produce infectious virus progenies. Transcription of virus genome in these systems will be studied by DNA-RNA hybridization kinetics and transcribed DNA fragments will be identified by blotting hybridization. Virus DNA replication will be tested by in situ hybridization and the synthesized virus DNA will be analyzed for the restriction enzyme digestion pattern by agarose gel electrophoresis. Proteins induced after infection or superinfection will be analyzed by SDS acrylamide gel electrophoresis. Recovery of progeny virus will be tested by transformation and superinfection assays. Attempts for transformation of human cord blood cells with virus DNA will be continued. DNA of a new EBV isolates and of EBV-like primate virus will be analyzed by blotting hybridization as to what differences the map of new EBV DNA has from B95 virus DNA map (Given & Kieff, 1978) and which fragments of EBV DNA the primate virus DNA can hybridize with. The relation between EBV and nasopharyngeal carcinoma will be examined in North America and Malaysia from which tumors can be obtained.